At 4km deep, the Mponeng mine, near Johannesburg, holds the Guinness World Record for being the deepest gold mine on Earth.
Its walls reach over 60°C/140°F, and humidity levels can often exceed 95%. More than 6,000 tonnes of ice slurry is pumped into underground reservoirs, and giant fans circulate the cooled air through the mine.
Every day, about 5,000 lbs of explosives are used, and 6,400 tonnes of rocks are excavated.
It’s fascinating to think about how much work is done in such a harsh environment every day to produce gold.